1. Field of the Invention
This invention relates to data conversion. In particular, the invention relates to dynamic element matching circuits.
2. Description of Related Art
Fast analog-to-digital converters often use a pipeline approach in which several stages of conversion are cascaded, each with a smaller number of bits. Each stage includes an analog-to-digital converter followed by a digital-to-analog converter.
Digital-to-analog converters tend to generate errors correlated to the digital input. These errors are typically the result of component mismatches, process and thermal gradients, and other non-linear error sources. These errors may create harmonic distortion that causes undesirable effects to the conversion process. Methods to reduce these errors include selecting high quality components, and trimming component values and parameters. However, these methods are expensive and difficult to implement. Dynamic element matching was first proposed by Rudy Van de Plassche in the 1970""s. More recent articles have appeared in the Journal of Solid State Circuits by Carley and others where the technique is most often used in sigma-delta converters with multi-bit quantizers where linearity is not inherent.